JP2013236046A - Circuit board and process of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board including a downsized coil and a process of manufacturing the same.SOLUTION: The circuit board includes a first insulating layer, a first magnetic material layer formed by plating on the first insulating layer, a plane coil formed on first magnetic material layer, and a second magnetic material layer formed by plating on the plane coil.

Description

  The present invention relates to a wiring board and a method for manufacturing the wiring board.

  Conventionally, four C-shaped coil patterns are formed on the surface of three layers of a build-up multilayer substrate, and the coil patterns are connected by a build-up via to form a spiral coil as a whole. There was a pattern coil on the printed circuit board.

JP 2001-077538 A

  However, since the conventional pattern coil has a large size as a component, it has been difficult to mount it in a package of an arithmetic processing unit such as a CPU (Central Processing Unit).

  Accordingly, it is an object of the present invention to provide a wiring board including a miniaturized coil and a method of manufacturing the wiring board.

  A wiring board according to an embodiment of the present invention is formed on a first insulating layer, a first magnetic layer formed by plating on the first insulating layer, and the first magnetic layer. A planar coil and a second magnetic layer formed by plating on the planar coil are included.

  It is possible to provide a wiring board including a coil with a reduced size and a method of manufacturing the wiring board.

It is a figure which shows the wiring board unit 10 of a comparative example. 1 is a diagram showing a wiring board 100 according to a first embodiment. It is a figure which shows wiring board unit 200A, 200B, 200C to which the wiring board 100 of Embodiment 1 is applied. FIG. 6 is a diagram showing a manufacturing process of the wiring board 100 of the first embodiment. FIG. 6 is a diagram showing a manufacturing process of the wiring board 100 of the first embodiment. FIG. 6 is a diagram showing a manufacturing process of the wiring board 100 of the first embodiment. FIG. 6 is a diagram showing a manufacturing process of the wiring board 100 of the first embodiment. 6 is a cross-sectional view showing a wiring board 100 according to a modification of the first embodiment. FIG. 6 is a cross-sectional view showing a wiring board 200 according to a second embodiment. It is a figure which shows the manufacturing process of the wiring board 200 of Embodiment 2. FIG. FIG. 10 is a cross-sectional view showing a wiring board 200 of a modification of the second embodiment.

  Embodiments to which a wiring board and a method for manufacturing a wiring board according to the present invention are applied will be described below.

  First, before explaining the wiring board of the embodiment and the method of manufacturing the wiring board, the wiring board of the comparative example and its problems will be explained.

<Comparative example>
FIG. 1 is a view showing a wiring board unit 10 of a comparative example.

  The wiring board unit 10 of the comparative example includes a mother board 20, a package board 30, a CPU 40, and a power supply circuit 50.

  The wiring board unit 10 is used, for example, in electronic devices such as a mobile phone terminal, a smart phone terminal, and a game machine.

  The mother board 20 is, for example, an FR-4 (Flame Retardant type 4) standard wiring board, and is produced by, for example, laminating a plurality of wiring layers and a plurality of insulating layers. On the mother board 20, a package substrate 30 on which the CPU 40 is mounted is mounted by a BGA (Ball Grid Array) solder 31 and a power supply circuit 50 is mounted.

  The package substrate 30 is mounted with a CPU 40 and functions as an interposer. The package substrate 30 is a wiring substrate such as a build-up substrate, for example, and is manufactured by stacking a plurality of wiring layers and a plurality of insulating layers, for example.

  The CPU 40 is an arithmetic processing device that performs arithmetic processing of an electronic device on which the wiring board unit 10 is mounted. The power output from the power supply circuit 50 is supplied to the CPU 40 via the mother board 20 and the package substrate 30.

  The power supply circuit 50 is a circuit that steps down power supplied from a battery (not shown) or an external power supply to generate a drive voltage for the CPU 40 and supplies the CPU 40 with power. The power supply circuit 50 includes electronic components such as a switching element SW, a coil L, a capacitor C, and an IC (Integrated Circuit). The switching element SW, the coil L, and the capacitor C constitute a step-down circuit, and the switching element SW is driven by an IC that functions as a controller, and outputs power rectified by the coil L and the capacitor C.

  In such a wiring board unit 10, the coil L of the power supply circuit 50 needs a certain amount of inductance, and is usually covered with a magnetic material in order to increase the inductance, and therefore has a relatively large size. In particular, when a coil that is commercially available as a general-purpose electronic component is used as the coil L of the power supply circuit 50, since the coil L has a certain height, it is not possible to mount the power supply circuit 50 on the package substrate 30. However, the power supply circuit 50 is disposed outside the package substrate 30.

  As described above, when the power supply circuit 50 is arranged outside the package substrate 30, the power output from the power supply circuit 50 is supplied to the CPU 40 through the mother board 20 and the package substrate 30.

  For this reason, the impedance of the power supply path (motherboard 20 and package substrate 30) between the CPU 40 and the power supply circuit 50 becomes high, and there arises a problem that the efficiency of power supply decreases.

  Further, in order to reduce the impedance of the power supply path, it is necessary to increase the size of the power plane and the ground plane. Therefore, the wiring board unit 10 configured as shown in FIG. In order to improve the efficiency, it is necessary to increase the size of the mother board 20 or the package substrate 30. Such an increase in size of the wiring board has a problem that it is difficult to realize in an electronic device.

  Further, when the size of the power plane and the ground plane is increased, the arrangement of each plane is restricted in the mother board 20 and the package substrate 30 in relation to the wiring such as I / O wiring. There's a problem.

  These problems are particularly remarkable in the package substrate 30 having a smaller size than the mother board 20.

  Here, for example, similarly to the printed circuit board of Patent Document 1, it is conceivable to construct a coil using the wiring of the mother board 20 or the package board 30. However, in order to increase the inductance, it is necessary to dispose the magnetic material near the coil.

  Here, in the mother board 20 or the package board 30 using a general wiring board as in the comparative example, a magnetic material cannot be incorporated in the manufacturing process. For this reason, it is difficult to form a coil for the power supply circuit 50 on the mother board 20 or the package substrate 30 of the comparative example.

  Further, when the coil is constructed using the wiring of the mother board 20 or the package substrate 30 without arranging the magnetic body on the mother board 20 or the package substrate 30, it is necessary to enlarge the coil in order to increase the inductance. For this reason, the problem that the motherboard 20 or the package board | substrate 30 will enlarge arises.

  Further, when the parasitic capacitance is increased by increasing the size of the power plane or the ground plane, or when the parasitic capacitance of the power supply circuit 50 is large, a capacitor for canceling the parasitic capacitance is provided. It is necessary to provide it. When such a capacitor is provided, there is a problem in that the mother board 20 or the package substrate 30 is increased in size because of restrictions on the arrangement of the capacitor in relation to other wiring.

  As described above, the wiring board unit 10 of the comparative example cannot reduce the size of the coil L of the power supply circuit 50, thereby reducing the power supply efficiency, increasing the size of the wiring board, each electronic component, power plane, and ground. Various problems such as restrictions on the arrangement of planes have occurred.

  Therefore, in the following, it is an object to provide a wiring board that solves these problems and a method of manufacturing the wiring board.

<Embodiment 1>
2A to 2D are diagrams showing the wiring substrate 100 of the first embodiment.

  FIG. 2A is a diagram showing a cross section of the wiring substrate 100 of the first embodiment. As shown in FIG. 2A, the wiring substrate 100 of the first embodiment includes a core substrate 110, wiring layers 120 (120A, 120B, 120C), an insulating layer 130, an insulating layer 140, a coil 150, and wirings 160A, 160B. , Wiring layer 170 (170A, 170B, 170C), insulating layer 180, and insulating layer 190. Further, the wiring substrate 100 of the first embodiment further includes through holes 400A and 400B, vias 401A, 401B, 402A and 402B, and wiring layers 403A, 403B, 404A, 404B, 405 and 406.

  2A, the wiring layer 120, the insulating layer 130, the insulating layer 140, the coil 150, and the wirings 160A and 160B are disposed on the upper side of the core substrate 110, and the wiring layer 170, The state in which the insulating layer 180 and the insulating layer 190 are provided is shown. However, the vertical relationship is merely a positional relationship for convenience of description, and the wiring board 100 can be used in an upside down state, or can be arranged at an arbitrary angle.

  Similarly, in the following, in the drawings, the upper surface is referred to as the upper surface, and the lower surface is referred to as the lower surface, but the upper surface and the lower surface are names for convenience of description, and are not universally upper and lower surfaces. If the wiring board 100 shown in FIG. 2 is turned upside down, the upper surface becomes the lower surface and the lower surface becomes the upper surface.

  FIG. 2B is a diagram illustrating a planar shape of the magnetic layer 155 included in the coil 150 of the wiring board 100 according to the first embodiment. FIG. 2C is a diagram illustrating a planar shape of the coil portion 153 and the resist layer 154 included in the coil 150 of the wiring substrate 100 according to the first embodiment. FIG. 2D is a diagram illustrating a planar shape of the magnetic layer 151 included in the coil 150 of the wiring substrate 100 according to the first embodiment.

  As shown in FIG. 2A, the core substrate 110 is obtained by, for example, forming wiring layers 120 and 170 on both surfaces of a base material obtained by impregnating a glass cloth base material with an epoxy resin. Through holes 400 </ b> A and 400 </ b> B are formed in the core substrate 110. The through holes 400 </ b> A and 400 </ b> B are produced by forming a copper plating film on the inner wall of the through hole formed in the core substrate 110 by, for example, plating or filling the through hole with copper plating.

  The wiring layers 120A and 170A are connected to the upper and lower ends of the through hole 400A, respectively. Also, wiring layers 120B and 170B are connected to the upper and lower ends of the through hole 400B, respectively.

  The wiring layer 120 is disposed on the upper surface of the core substrate 110. The wiring layer 120 has a predetermined pattern of wiring in plan view. Here, the wiring layer 120 will be described as being formed on the upper surface of the core substrate 110.

  The wiring layer 120 is divided into wiring layers 120A, 120B, and 120C. The wiring layers 120A, 120B, and 120C are formed by patterning a copper foil provided on the upper surface of the core substrate 110, for example.

  The wiring layer 120A has a lower surface connected to the through hole 400A and an upper surface connected to the via 401A. The wiring layer 120B has a lower surface connected to the through hole 400B and an upper surface connected to the via 401B. In the following description, the wiring layers 120A, 120B, and 120C are referred to as the wiring layer 120 unless particularly distinguished.

  The insulating layer 130 is an insulating layer disposed on the upper surface of the wiring layer 120 and is an example of a first insulating layer. The insulating layer 130 is an insulating layer that serves as a foundation when the coil 150 is formed.

  The insulating layer 130 is a film-like insulating layer formed of, for example, an epoxy resin or a polyimide resin, and is an example of an insulating layer included in the build-up substrate.

  The insulating layer 140 is an insulating layer disposed on the upper surfaces of the insulating layer 130 and the coil 150 via the insulating film 152, and is an example of a second insulating layer. The insulating layer 140 is a film-like insulating layer formed of, for example, an epoxy resin or a polyimide resin, and is an example of an insulating layer included in the build-up substrate.

  The coil 150 is formed inside the insulating layer 140 on the upper surface of the insulating layer 130. The coil 150 includes a magnetic layer 151, an insulating film 152, a coil portion 153, an insulating resin 154, and a magnetic layer 155. The coil 150 is a planar coil, and one end 153A and the other end 153B of the coil portion 153 are connected to wirings 160A and 160B via vias 156A and 156B, respectively. The vias 156A and 156B are connected to the one end 153A and the other end 153B of the coil part 153 through the opening part opened in the insulating film 152, respectively.

  The magnetic layer 151 is formed on the upper surface of the insulating layer 130 as shown in FIG. The magnetic layer 151 is patterned in a rectangular shape in plan view as shown in FIG. The magnetic body 151 is larger in plan view than the coil portion 153 (see FIG. 2C) formed on the upper side, and is disposed so as to include the coil 153 in plan view.

  The magnetic layer 151 is made of, for example, an alloy of zinc and ferrite (Zn-Fe), and is formed of an alloy plating film of zinc and ferrite. The magnetic layer 151 is an example of a first magnetic layer. Since the ferrite alloy (Zn—Fe) formed by the plating process has a relatively high resistance (about 100Ω), it is suitable for forming the coil portion 153. Note that the thickness of the magnetic layer 151 may be 5 μm to 10 μm, for example.

  As shown in FIG. 2A, the insulating film 152 is formed between the insulating layers 130 and 140, the upper surface of the magnetic layer 151, a partial upper surface of the coil portion 153, and the upper surface of the magnetic layer 155. Yes. The insulating film 152 is an example of an insulating film. Details of a portion where the insulating film 152 is formed will be described together with a manufacturing process. The insulating film 152 is formed of a resin film such as polyimide, for example. The thickness of the insulating film 152 is, for example, 3 μm to 10 μm.

  As shown in FIG. 2A, the coil portion 153 is formed on the insulating film 152 formed on the upper surface of the magnetic layer 151. As shown in FIG. 2C, the coil portion 153 is a planar coil (planar coil) wound in a rectangular spiral shape in plan view, and has one end 153A and the other end 153B. The coil portion 153 can also be referred to as a spiral coil.

  The coil part 153 is made of copper, for example, and is formed by a plating process. What is necessary is just to set the thickness of the coil part 153 to 10 micrometers-20 micrometers, for example.

  The coil portion 153 is wound twice in a clockwise shape from one end 153A to the other end 153B. Here, although the coil part 153 with 2.5 turns is shown, the number of turns of the coil part 153 may be determined in accordance with the inductance required depending on the application. The number of turns of the coil portion 153 may be, for example, about 100 turns or more.

  Note that one end 153A of the coil portion 153 is connected to the wiring 160A by a via 156A, and the other end 153B is connected to the wiring 160B by a via 156B.

  Further, as shown in FIG. 2C, an insulating resin 154 (portion indicated by a dot) is formed on the coil portion 153 except for the periphery of one end 153A and the periphery of the other end 153B. Yes. When the magnetic layer 151 or 155 enters between the windings of the coil portion 153, the inductance of the coil 150 is reduced. In order to suppress the occurrence of such a problem, an insulating resin 154 is formed between the windings of the coil portion 153.

  In addition, since the coil part 153 is wound planarly in this way, the coil 150 is a planar coil.

  As shown in FIG. 2A, the insulating resin 154 is formed in a part of the gap of the coil portion 153. The insulating resin 154 is an example of an insulating part. The region where the insulating resin 154 is formed is a region excluding the periphery of the one end 153A and the periphery of the other end 153B inside the coil portion 153, as indicated by dots in FIG. . As the insulating resin 154, for example, a photosensitive epoxy resin can be used.

  As shown in FIG. 2A, the magnetic layer 155 includes an upper surface other than the one end 153A and the other end 153B of the coil unit 153, a part of the side surface of the coil unit 153, and a part of the upper surface of the polyimide film 151. It is formed so as to cover.

  The magnetic layer 155 is made of, for example, an alloy of zinc and ferrite (Zn—Fe), and is formed of an alloy plating film of zinc and ferrite. The magnetic layer 155 is an example of a second magnetic layer.

  As shown in FIG. 2B, the magnetic layer 155 has an opening 155A in the center in plan view. As shown in FIG. 2A, the opening 155A is formed so as to be positioned above the one end 153A of the coil portion 153. That is, the opening 155 </ b> A is formed so that the magnetic layer 155 avoids one end 153 </ b> A of the coil portion 153. The length of the magnetic layer 155 in the horizontal direction in the drawing is shorter than that of the magnetic layer 151 (see FIG. 2D), and the other end 153B of the coil portion 153 is a magnetic layer in plan view. 155 is not covered. Note that the thickness of the magnetic layer 155 may be, for example, 5 μm to 10 μm. Moreover, what is necessary is just to set the thickness from the lower surface of the magnetic body layer 151 to the upper surface of the magnetic body layer 155 to 40 micrometers-60 micrometers including the thickness of the coil part 153, for example.

  The vias 156A and 156B connect the one end 153A and the other end 153B of the coil portion 153 and the wirings 160A and 160B, respectively. The via 156A is an example of a first via, and the via 156B is an example of a second via.

  The wirings 160A and 160B are formed on the upper surface of the insulating layer 140, and are connected to the one end 153A and the other end 153B of the coil portion 153 via the vias 156A and 156B, respectively. The wiring 160A is an example of a first wiring part, and the wiring 160B is an example of a second wiring part.

  The wiring layer 170 is disposed on the lower surface of the core substrate 110. The wiring layer 170 may have a predetermined pattern of wiring in plan view. Here, the wiring layer 170 will be described as being formed on the lower surface of the core substrate 110.

  The wiring layer 170 is divided into wiring layers 170A, 170B, and 170C. The wiring layers 170A, 170B, and 170C are formed, for example, by patterning a copper foil provided on the lower surface of the core substrate 110.

  The wiring layer 170A has an upper surface connected to the through hole 400A and a lower surface connected to the via 402A. The wiring layer 170B has an upper surface connected to the through hole 400B and a lower surface connected to the via 402B. Hereinafter, the wiring layers 170A, 170B, and 170C will be referred to as the wiring layer 170 unless otherwise distinguished.

  The insulating layer 180 is an insulating layer disposed on the lower surface of the wiring layer 170. The insulating layer 180 has the same thickness as the insulating layer 130. The insulating layer 180 is a film-like insulating layer formed of, for example, an epoxy resin or a polyimide resin, and is an example of an insulating layer included in the build-up substrate.

  The insulating layer 190 is an insulating layer formed on the lower surface of the insulating layer 180. The insulating layer 190 is a film-like insulating layer formed of, for example, an epoxy resin or a polyimide resin, and is an example of an insulating layer included in the build-up substrate.

  Through hole 400A has an upper end connected to wiring layer 120A and a lower end connected to wiring layer 170A. Through hole 400B has an upper end connected to wiring layer 120B and a lower end connected to wiring layer 170B.

  The via 401A is formed in a hole that penetrates the insulating layers 130 and 140 and the insulating film 152 from the surface of the insulating layer 140 to the surface of the wiring layer 120A. The via 401A is formed, for example, by filling the hole with copper plating by a semi-additive method. The via 401A is formed integrally with the wiring layer 403A. That is, the lower end of the via 401A is connected to the wiring layer 120A, and the upper end is connected to the wiring layer 403A.

  The via 401B is formed in a hole that penetrates the insulating layers 130 and 140 and the insulating film 152 from the surface of the insulating layer 140 to the surface of the wiring layer 120B. The via 401B is formed, for example, by filling the hole with copper plating by a semi-additive method. The via 401B is formed integrally with the wiring layer 403B. That is, the lower end of the via 401B is connected to the wiring layer 120B, and the upper end is connected to the wiring layer 403B. The wirings 403A and 403B are formed on the upper surface of the insulating layer 140.

  The via 402A is formed in a hole that penetrates the insulating layers 180 and 190 from the surface (lower surface) of the insulating layer 190 to the surface (lower surface) of the wiring layer 170A. The via 402A is formed, for example, by filling the hole with copper plating by a semi-additive method. The via 402A is formed integrally with the wiring layer 404A. That is, the upper end of the via 402A is connected to the wiring layer 170A, and the lower end is connected to the wiring layer 404A.

  The via 402B is formed in a hole that penetrates the insulating layers 180 and 190 from the surface (lower surface) of the insulating layer 190 to the surface (lower surface) of the wiring layer 170B. The via 402B is formed, for example, by filling the hole with copper plating by a semi-additive method. The via 402B is formed integrally with the wiring layer 404B. That is, the upper end of the via 402B is connected to the wiring layer 170B, and the lower end is connected to the wiring layer 404B. The wirings 404A and 404B are formed on the lower surface of the insulating layer 190.

  The wirings 405 and 406 are formed between the wiring layer 404A and the wiring layer 404B on the lower surface of the insulating layer 190. The wirings 405 and 406 are formed by, for example, a semi-additive method.

  The wiring substrate 100 according to the first embodiment includes the coil 150 having the magnetic layer 151, the coil portion 153, and the magnetic layer 155 formed by plating.

  Since the magnetic layer 151, the coil portion 153, and the magnetic layer 155 of the coil 150 can be formed by plating, they can be easily formed inside the wiring substrate 100.

  The coil portion 153 is covered with magnetic layers 151 and 155 except for one end 153A and the other end 153B. The magnetic layers 151 and 155 cover the upper surface, the lower surface, and some side surfaces of the coil portion 153.

  For this reason, the inductance of the coil part 153 can be improved and the coil part 153 can be reduced in size compared with the case where the magnetic body layers 151 and 155 are not formed.

  3A to 3C are diagrams showing wiring board units 200A, 200B, and 200C to which the wiring board 100 of the first embodiment is applied. 3A to 3C, the same components as those in the wiring board unit 10 of the comparative example (see FIG. 1) are denoted by the same reference numerals, and the description thereof is omitted.

  A wiring board unit 200A shown in FIG. 3A includes a mother board 20, a package board 230A, a CPU 240A, and a power supply circuit 250.

  The wiring board unit 200A is used in electronic devices such as a mobile phone terminal, a smart phone terminal, and a game machine, for example.

  On the mother board 20, a package substrate 230A on which a CPU 240A is mounted is mounted by a BGA (Ball Grid Array) solder 31 and a power supply circuit 250 is mounted.

  The package substrate 230A is mounted with a CPU 240A and functions as an interposer. The package substrate 230A is a wiring substrate such as a build-up substrate, for example, and is manufactured by stacking a plurality of wiring layers and a plurality of insulating layers, for example.

  The package substrate 230A uses the wiring substrate 100 shown in FIG. 2A as a package substrate, and includes a coil 150. The coil 150 is electrically connected to the IC and the switching element SW built in the CPU 240A and the capacitor C mounted on the package substrate 230A to construct the power supply circuit 260A.

  The CPU 240A is an arithmetic processing device that performs arithmetic processing of an electronic device on which the wiring board unit 200A is mounted. The CPU 240A includes a switching element SW and an IC for constructing the power supply circuit 260A. This IC functions as a controller for the power supply circuit and drives the switching element.

  Power is supplied to the CPU 240A from a power supply circuit 260A constructed by a coil 150 built in the package substrate 230A, an IC and switching element SW built in the CPU 240A, and a capacitor C mounted on the package substrate 230A. The The capacitor C may be a capacitor as a chip component.

  The power supply circuit 250 steps down power supplied from a battery (not shown) or an external power supply, and is mounted on the coil 150 built in the package substrate 230A, the IC and switching element SW built in the CPU 240A, and the package substrate 230A. Power is supplied to a power supply circuit 260A constructed by the capacitor C.

  The power supply circuit 250 includes a switching element SW, a coil L, a capacitor C, and an IC. The switching element SW, the coil L, and the capacitor C constitute a step-down circuit, and the switching element SW is driven by an IC that functions as a controller, and outputs power rectified by the coil L and the capacitor C.

  In such a wiring board unit 200A, the power supply circuit 250 steps down the voltage supplied from a power supply (not shown) and supplies it to the power supply circuit 260A, and the power supply circuit 260A further steps down the voltage and supplies it to the CPU 240A.

  A part of the power supply circuit 260A (IC, switching element SW) is included in the CPU 240A, the capacitor C is mounted on the package substrate 230A, and the coil 150 is included in the package substrate 230A. In other words, the power supply circuit 260A is located in a place that is far closer to the CPU 240A than the power supply circuit 250.

  For this reason, for example, it is assumed that power having a voltage value of 5V is supplied from a power source such as a battery to the power supply circuit 250, and power that has been stepped down to 3V by the power supply circuit 250 is supplied to the power supply circuit 260A. Then, it is assumed that power having a voltage value of 3V is stepped down to 1V by the power supply circuit 260A and supplied to a core (not shown) of the CPU 240A.

  As described above, when the power supply voltage of 5V is stepped down to 1V and supplied to the CPU 240A, the conversion from 3V to 1V is performed by the power supply circuit 260A located in the immediate vicinity of the core of the CPU 240A.

  Therefore, for example, in the wiring board unit 200A of the first embodiment, in the wiring board unit 10 of the comparative example (see FIG. 1), the power supply circuit 50 steps down the power supply voltage of 5V to 1V and supplies it to the CPU 40. Compared to the above, the efficiency of power supply can be improved.

  The reason why the power supply efficiency can be improved in this way is that the wiring substrate 100 (see FIG. 2A) of the first embodiment used as the package substrate 230A includes a small coil 150 having a high inductance. .

  Since the coil 150 includes magnetic layers 151 and 155 that can be formed by plating and a coil portion 153 that is formed by plating, the coil 150 can be formed in a small space inside the wiring substrate 100 (package substrate 230A). Further, a high inductance required for the power supply circuit 260A can be realized.

  Therefore, the wiring board unit 200A of the first embodiment can improve the power supply efficiency compared to the wiring board unit 10 of the comparative example (see FIG. 1).

  In addition, the coil portion 153 of the coil 150 is covered with magnetic layers 151 and 155 in most of the outer periphery (the portion excluding the one end 153A and the other end 153B). For this reason, noise generated from the coil due to switching of the switching element SW hardly passes through the magnetic layers 151 and 155. For this reason, it is possible to prevent noise from being transmitted from the coil 150 to the CPU 240A or the like.

  For example, when a printed circuit board whose coil is not covered with a magnetic material, such as a conventional printed circuit board, is used as the package substrate 230A shown in FIG. 3A, noise due to switching is radiated from the coil. There is a risk of adverse effects.

  On the other hand, the wiring board unit 200A of the first embodiment can suppress an adverse effect on the operation of the CPU 240A. Thus, by suppressing the influence of noise, it is possible to provide a wiring board unit 200A having excellent noise resistance such as EMS (Electro Magnetic Susceptance) or EMI (Electro Magnetic Interference).

  In addition, since the power supply circuit 260A is a low-voltage power supply with an output voltage of 1V, it is possible to mount an IC functioning as a controller and a switching element SW inside the CPU 240A, thereby improving the efficiency of the power supply circuit. Thus, POL (Point Of Load) can be realized.

  FIG. 3B is a diagram showing a wiring board unit 200B of another form.

  The wiring board unit 200B includes a mother board 20, a package board 230B, and a CPU 240B.

  Wiring board unit 200B is used for electronic devices, such as a mobile phone terminal, a smart phone terminal, and a game machine, for example.

  A package substrate 230B on which the CPU 240B is mounted is mounted on the mother board 20 by a BGA (Ball Grid Array) solder 31.

  The package substrate 230B is mounted with a CPU 240B and functions as an interposer. The package substrate 230B is a wiring substrate such as a build-up substrate, for example, and is manufactured by stacking a plurality of wiring layers and a plurality of insulating layers, for example.

  The package substrate 230 </ b> B uses the wiring substrate 100 shown in FIG. 2A as a package substrate, and includes a coil 150. The coil 150 is electrically connected to the IC and switching element SW built in the CPU 240B and the capacitor C mounted on the package substrate 230B, thereby constructing a power supply circuit 260B.

  The CPU 240B is an arithmetic processing device that performs arithmetic processing of an electronic device on which the wiring board unit 200B is mounted. The CPU 240B includes a switching element SW and an IC for constructing the power supply circuit 260B. This IC functions as a controller for the power supply circuit and drives the switching element.

  The core of the CPU 240B has power from a power supply circuit 260B constructed by a coil 150 built in the package substrate 230B, an IC and switching element SW built in the CPU 240B, and a capacitor C mounted on the package substrate 230B. Is supplied.

  In such a wiring board unit 200B, the power supply circuit 260B steps down the voltage supplied from a power supply (not shown) and supplies it to the core of the CPU 240B and the like.

  A part of the power supply circuit 260B (IC, switching element SW) is included in the CPU 240B, the capacitor C is mounted on the package substrate 230B, and the coil 150 is included in the package substrate 230B. That is, the power supply circuit 260B is located in a place that is far closer to the CPU 240B than the power supply circuit 50 (see FIG. 1) of the wiring board unit 10 of the comparative example.

  For this reason, for example, power having a voltage value of 5V is directly supplied from a power source such as a battery to the power supply circuit 260B, and the power reduced to 1V by the power supply circuit 260B is supplied to a core (not shown) of the CPU 240B.

  As described above, in the wiring board unit 200B shown in FIG. 3B, the power supply voltage of 5V is stepped down to 1V by the power supply circuit 260B located in the immediate vicinity of the core of the CPU 240B.

  Therefore, for example, in the wiring board unit 200B of the first embodiment, in the wiring board unit 10 of the comparative example (see FIG. 1), the power supply circuit 50 steps down the power supply voltage of 5V to 1V and supplies it to the CPU 40. Compared to the above, the efficiency of power supply can be improved.

  In addition, the efficiency of power supply can be further improved as compared with the wiring board unit 200A shown in FIG.

  The reason why the power supply efficiency can be improved in this way is that the wiring substrate 100 (see FIG. 2A) of the first embodiment used as the package substrate 230B includes a small coil 150 having a high inductance. . The coil 150 can realize a high inductance required for the power supply circuit 260B.

  For this reason, the wiring board unit 200B of Embodiment 1 can improve the efficiency of power supply compared with the wiring board unit 10 of the comparative example (see FIG. 1).

  Further, the wiring board unit 200B illustrated in FIG. 3B can suppress noise from being transmitted from the coil 150 to the CPU 240B and the like, similarly to the wiring board unit 200A illustrated in FIG.

  FIG. 3C is a diagram showing another form of wiring board unit 200C.

  The wiring board unit 200C includes a mother board 220, a package board 230C, and a CPU 240C.

  The wiring board unit 200C is used for electronic devices such as a mobile phone terminal, a smart phone terminal, and a game machine, for example.

  On the motherboard 220, a package substrate 230C on which the CPU 240C is mounted is mounted by a BGA (Ball Grid Array) solder 31. The motherboard 220 is a wiring board such as an FR-4 standard wiring board or a build-up board, for example, and is manufactured by stacking a plurality of wiring layers and a plurality of insulating layers, for example.

  The motherboard 220 uses the wiring board 100 shown in FIG. 2A as a motherboard, and includes a coil 150. The coil 150 is electrically connected to the IC and the switching element SW built in the CPU 240C and the capacitor C mounted on the package substrate 230C, thereby constructing a power supply circuit 260C.

  The package substrate 230C is mounted with a CPU 240C and functions as an interposer. The package substrate 230C is a wiring substrate such as a build-up substrate, for example, and is manufactured by stacking a plurality of wiring layers and a plurality of insulating layers, for example.

  The package substrate 230C can be the same as the package substrate 30 of the comparative example. That is, the package substrate 230C may not include the coil 150. However, the package substrate 230C may include the coil 150. In this case, the power supply circuit includes the coil 150 included in the motherboard 220, the coil 150 included in the package substrate 230C, the IC and switching element SW built in the CPU 240C, and the capacitor C mounted on the package substrate 230C. 260C may be constructed.

  The CPU 240C is an arithmetic processing device that performs arithmetic processing of an electronic device on which the wiring board unit 200C is mounted. The CPU 240C includes a switching element SW and an IC for constructing the power supply circuit 260C. This IC functions as a controller for the power supply circuit and drives the switching element.

  The core of the CPU 240C receives power from a power supply circuit 260C constructed by a coil 150 built in the motherboard 220, an IC and switching element SW built in the CPU 240C, and a capacitor C mounted on the package substrate 230C. Supplied.

  In such a wiring board unit 200C, the power supply circuit 260C steps down the voltage supplied from a power supply (not shown) and supplies it to the core of the CPU 240C.

  A part of the power supply circuit 260C (IC, switching element SW) is included in the CPU 240C, the capacitor C is mounted on the package substrate 230C, and the coil 150 is included in the motherboard 220. That is, the power supply circuit 260C is located in a place that is far closer to the CPU 240C than the power supply circuit 50 (see FIG. 1) of the wiring board unit 10 of the comparative example.

  For this reason, for example, power having a voltage value of 5V is directly supplied from a power source such as a battery to the power supply circuit 260C, and the power reduced to 1V by the power supply circuit 260C is supplied to a core (not shown) of the CPU 240C.

  As described above, in the wiring board unit 200C shown in FIG. 3B, the power supply voltage of 5V is stepped down to 1V by the power supply circuit 260C located in the immediate vicinity of the core of the CPU 240C.

  For this reason, in the wiring board unit 200C of the first embodiment, for example, in the wiring board unit 10 of the comparative example (see FIG. 1), the power supply circuit 50 steps down the power supply voltage of 5V to 1V and supplies it to the CPU 40. Compared to the above, the efficiency of power supply can be improved.

  In addition, the efficiency of power supply can be further improved as compared with the wiring board unit 200A shown in FIG.

  The reason why the power supply efficiency can be improved in this way is that the wiring board 100 (see FIG. 2A) of the first embodiment used as the mother board 220 includes a small coil 150 having a high inductance. The coil 150 can realize a high inductance required for the power supply circuit 260C.

  Therefore, the wiring board unit 200C of the first embodiment can improve the power supply efficiency compared to the wiring board unit 10 of the comparative example (see FIG. 1).

  Further, the wiring board unit 200C illustrated in FIG. 3B can suppress noise from being transmitted from the coil 150 to the CPU 240C and the like, similarly to the wiring board unit 200A illustrated in FIG.

  Next, a method for manufacturing the wiring substrate 100 according to the first embodiment will be described with reference to FIGS.

  4 to 7 are diagrams showing manufacturing steps of the wiring substrate 100 of the first embodiment.

  First, as shown in FIG. 4A, a core substrate 110 having wiring layers 120 and 170 formed on an upper surface and a lower surface is prepared, and insulating layers 130 and 180 are formed on the upper surface and the lower surface of the wiring layer 120, respectively. Form. In the core substrate 110, through holes 400A and 400B are formed in advance.

  The insulating layers 130 and 180 are formed by heating and pressurizing and laminating resin films with a vacuum laminator. As the resin film, for example, a resin film such as epoxy or polyimide can be used.

  Next, as shown in FIG. 4B, a mask 300 is formed using a photosensitive resist material on both ends of the upper surface of the insulating layer 130. This step may be performed, for example, by curing a photosensitive resist material applied on the insulating layer 130 in a photolithography step.

  Next, as shown in FIG. 4C, a magnetic layer 151 is formed in a portion of the upper surface of the insulating layer 130 where the mask 300 is not formed. The magnetic layer 151 can be formed by, for example, a spray plating process. This spray plating process may be performed using, for example, a Zn—Fe plating solution.

  The magnetic layer 151 is, for example, a film thickness of 10 μm and 0.85 mm (vertical direction: a direction penetrating the drawing) × 2 mm (horizontal direction: a horizontal direction in the drawing) in a plan view. Is a size for setting 7 nH.

The composition of the Zn—Fe alloy used as the magnetic layer 151 is, for example, Zn _0.36 —Fe _2.54 O ₄ . As the magnetic layer 151, for example, nickel (Ni), cobalt (Co), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) can be used instead of the Zn-Fe alloy. ), Barium (Ba), manganese (Mn), etc., and ferrite (Fe).

  Next, after removing the mask 300, an insulating film 152A is formed on the top surfaces of the insulating layer 130 and the magnetic layer 151, as shown in FIG. The insulating film 152A is a part of the insulating film 152 illustrated in FIG. 2A and is an example of a first insulating film. The insulating film 152A is formed in order to improve the adhesion between the magnetic layer 151 and the coil portion 153 by providing minute unevenness. The thickness of the insulating film 152A may be 2 to 5 μm, for example.

  The removal of the mask 300 may be performed by an etching process using a stripping solution, for example. The insulating film 152A may be formed, for example, by applying a varnish-like polyimide resin by a spin coating method. Note that an epoxy resin may be used instead of the polyimide resin.

  Next, as shown in FIG. 5A, a seed layer 153C is formed on the top surface of the insulating film 152A. The seed layer 153 </ b> C is a seed (seed) portion that becomes the coil portion 153 by performing an electrolytic plating process on the upper surface later.

  The seed layer 153C can be formed, for example, by sputtering copper. The seed layer 153C can be produced by forming a copper thin film by an electroless plating process. The film thickness of the seed layer 153C is, for example, 0.5 μm to 0.8 μm.

  Next, as shown in FIG. 5B, a mask 301 is formed on the upper surface of the seed layer 153C using a photosensitive resist material. This step may be performed, for example, by curing the photosensitive resist material applied to the seed layer 153C in a photolithography step. The mask 301 is used when the coil portion 153 is formed later by electrolytic plating. Therefore, the mask 301 may be patterned so that the coil portion 153 (see FIG. 2C) can be formed in a plan view.

  Next, as shown in FIG. 5C, a copper coil portion 153 is formed by electrolytic plating. This electrolytic plating process may be performed while supplying power to the seed layer 153C. What is necessary is just to set the film thickness of the coil part 153 to 20 micrometers, for example. For example, the seed layer 153 may be formed on a portion of the final product that is not left as the wiring substrate 100 (a portion that will be removed later), and this portion may be used as a power supply pattern.

  Next, the mask 301 and the portion of the seed layer 153C (see FIG. 5C) exposed from the coil portion 153 are removed, and the coil portion 153 is exposed as shown in FIG. 5D. For example, the mask 301 may be removed by an etching process using a stripping solution. The removal of the seed layer 153C may be performed by, for example, a reverse sputtering method.

  Note that in this reverse sputtering method, the portion formed between the coil portion 153 (see FIG. 5D) and the insulating film 152A in the seed layer 153C formed in the step shown in FIG. Since it is integrated with the coil portion 153, it remains without being removed.

  The coil portion 153 thus obtained has line / space = 120 μm / 20 μm and 2.5 turns.

  Note that the seed layer 153C may be removed by a wet etching method instead of the reverse sputtering method.

  Next, as illustrated in FIG. 6A, an insulating resin 154 is formed between the windings of the coil portion 153. The insulating resin 154 is formed in a region indicated by a dot in FIG. For example, after applying a photosensitive resin on the coil portion 153 including between the windings, unnecessary portions of the photosensitive resin can be removed by a photolithography process. As the insulating resin 154, for example, a photosensitive epoxy resin can be used.

  Next, as shown in FIG. 6B, a mask 302 is formed. The mask 302 can be formed, for example, by performing a photolithography process after applying a resist material. As the mask 302, for example, a photosensitive epoxy resin can be used.

  Since the mask 302 is used when the magnetic layer 155 is formed later, the mask 302 is patterned so as to obtain the magnetic layer 155 shown in a plan view in FIG. In FIG. 2 (B), it is formed on both right and left ends.

  Next, as shown in FIG. 6C, a magnetic layer 155 is formed using a mask 302. The magnetic layer 155 may be formed by, for example, a spray plating process using a Zn—Fe plating solution.

  The magnetic layer 155 has, for example, a film thickness of 10 μm, and 0.85 mm (vertical) × 0.85 mm (horizontal) in plan view. As an example, this is a size for setting the inductance of the coil 150 to 7 nH.

The composition of the Zn—Fe alloy used as the magnetic layer 155 is, for example, Zn _0.36- Fe _2.54 O ₄ . For example, nickel (Ni), cobalt (Co), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) can be used as the magnetic layer 155 instead of the Zn-Fe alloy. ), Barium (Ba), manganese (Mn), etc., and ferrite (Fe). This is the same as the magnetic body 151.

  Next, the mask 302 is removed, and an insulating film 152B is formed over the insulating film 152A, the one end 153A and the other end 153B of the coil portion 153, and the top surface of the magnetic layer 155, as shown in FIG. The insulating film 152B is formed to improve the adhesion between the magnetic layer 155 and the insulating layer 140. The insulating film 152B may be formed to a thickness of 2 to 5 μm, for example.

  The insulating film 152B is a part of the insulating film 152 illustrated in FIG. 2A and becomes the insulating film 152 (see FIG. 2A) together with the insulating film 152A formed in the step illustrated in FIG. . The insulating film 152B is an example of a second insulating film.

  For example, the mask 302 may be removed by an etching process using a stripping solution. The insulating film 152B may be formed by, for example, applying a varnish-like polyimide resin by a spin coating method. Note that when an epoxy resin is used instead of the polyimide resin as the insulating film 152A, an epoxy resin may be used instead of the polyimide resin as the insulating film 152B.

  Next, as illustrated in FIG. 7B, the insulating layer 140 is formed over the insulating film 152, and the insulating layer 190 is formed on the lower surface of the insulating layer 180.

  The insulating layers 140 and 190 are formed by laminating a resin film by heating and pressing with a vacuum laminator. As the resin film, for example, a resin film such as epoxy or polyimide can be used.

  Next, as illustrated in FIG. 7C, via holes 141 </ b> A and 141 </ b> B are formed in the insulating layer 140 and the insulating film 152. In addition, via holes 407A and 407B reaching the surfaces of the wiring layers 120A and 120B are formed in the insulating layer 140, the insulating film 152, and the insulating layer 130. In addition, via holes 408A and 408B reaching the surfaces (lower surfaces) of the wiring layers 170A and 170B are formed in the insulating layer 190 and the insulating layer 180.

  The via holes 141A, 141B, 407A, 407B, 408A, and 408B may be formed by laser processing, for example. Each of the via holes 141A and 141B has a shape in which the one end 153A and the other end 153B of the coil portion 153 are the bottom surface and an opening portion on the surface of the insulating layer 140. Has a frustoconical cross section. The via holes 141A and 141B are formed by removing the insulating film 152 on the bottom surface.

  The via holes 407A and 407B each have a shape in which the surface of the wiring layers 120A and 120B is a bottom surface and an opening on the surface of the insulating layer 140, and has a larger diameter on the opening side than the opening on the bottom side, for example. It has a frustoconical cross section.

  The via holes 408A and 408B each have a shape in which the surface of the wiring layers 170A and 170B is a bottom surface and an opening is formed on the surface (lower surface) of the insulating layer 190. For example, the diameter of the via hole 408A and 408B Has a frustoconical cross section.

  Next, as shown in FIG. 7D, vias 156A and 156B are formed in the via holes 141A and 141B, respectively, and wirings 160A and 160B are formed on the vias 156A and 156B, respectively.

  In addition, vias 401A, 401B, 402A, and 402B are formed in the via holes 407A, 407B, 408A, and 408B, respectively.

  The vias 156A and 156B may be formed by, for example, a semi-additive method. First, for the vias 156A, 156B, for example, a copper seed layer is formed on the sidewalls and bottom surfaces of the via holes 141A, 141B and the surface of the insulating layer 140 by electroless plating.

  Further, the vias 401A, 401B, 402A, and 402B may be formed by, for example, a semi-additive method. First, for the vias 401A and 401B, for example, a copper seed layer is formed on the sidewalls and bottom surfaces of the via holes 407A and 407B and the surfaces of the insulating layer 140, the insulating film 152, and the insulating layer 130 by electroless plating. In the vias 402A and 402B, for example, a copper seed layer is formed on the sidewalls and bottom surfaces of the via holes 408A and 408B and the surfaces of the insulating layers 180 and 190 by electroless plating.

  Next, a plating resist layer having openings having the shapes of the wirings 160A, 160B, 403A, and 403B is formed on the seed layer. Then, electrolytic plating is performed while supplying power to the seed layer, and an electrolytic copper plating film is deposited on the surface of the seed layer exposed from the plating resist layer, whereby vias 156A and 156B and wirings 160A and 160B are formed. While forming continuously, vias 401A and 401B and wirings 403A and 403B are formed continuously.

  Similarly, vias 402A and 402B and wirings 404A and 404B are continuously formed using a plating resist layer.

  Finally, the plating resist layer is removed, and the seed layer not included in the wirings 160A, 160B, 403A, 403B, 404A, 404B is removed. The plating resist layer may be removed by, for example, an etching process using a stripping solution, and the seed layer may be removed by, for example, a wet etching method.

  Note that the vias 156A, 156B, 401A, 401B, 402A, and 402B and the wirings 160A, 160B, 403A, 403B, 404A, and 404B may be formed by a subtractive method or other methods.

  As described above, the wiring substrate 100 of the first embodiment is completed.

  Wiring substrate 100 of the first embodiment includes a coil 150 that can be formed inside by plating. For this reason, by using the wiring board 100 as the package boards 230A, 230B or the motherboard 220 of the wiring board units 200A to 200C, voltage conversion can be performed in the immediate vicinity of the core of the CPU 240A, so that the power supply efficiency can be improved. Can be improved. This also makes it possible to reduce the size of the power supply circuit.

  Further, since the coil 150 realizing high inductance with the magnetic layers 151 and 155 can be manufactured inside the wiring substrate 100 in the same process as that for manufacturing a normal wiring substrate, the manufacturing cost can be reduced. .

  Further, since the coil portion 153 of the coil 150 is sandwiched between the magnetic layers 151 and 155 and has high noise resistance, the influence on the surrounding wiring and the like is extremely low, and the degree of freedom in designing the peripheral circuit can be improved. it can.

  In the above description, the wiring board 100 is a build-up board. However, the wiring board 100 is not limited to a build-up board. That is, the wiring substrate 100 may be any substrate as long as it is a substrate in which an insulating layer and a wiring layer are stacked.

  In the above description, the configuration in which one end 153A and the other end 153B of the coil 150 are connected to the wirings 160A and 160B via the vias 156A and 156B has been described. However, the one end 153A and the other end 153B do not necessarily have to be connected to the wirings 160A and 160B located above the wiring substrate 100 via the vias 156A and 156B. For example, at least one of the one end 153A and the other end 153B may be pulled out in the lateral direction of the wiring board 100 through the wiring layer.

  Also, in the above, the magnetic body layer 151 that is larger than the coil section 153 in plan view is provided on the lower surface side of the coil section 153 of the coil 150, and the magnetic body that covers the upper surface side of the coil section 153 except for the one end 153A and the other end 153B The mode of providing the layer 155 has been described.

  However, the magnetic layer 155 may expose portions other than the one end 153A and the other end 153B, and the magnetic layer 151 may expose a part of the lower surface of the coil portion 153. For example, when a sufficient space for forming the magnetic layer 151 or 155 cannot be secured due to the relationship with other wirings, a part of the coil portion 153 may be exposed in this way.

  In the above description, the wiring board 100 is a so-called build-up board with a core board that includes the core board 110. However, the wiring board 100 is a so-called coreless build-up board that does not include the core board 110. May be.

  Finally, a modification of the wiring substrate 100 of the first embodiment will be described with reference to FIG.

  FIG. 8 is a cross-sectional view showing a wiring board 100 according to a modification of the first embodiment. The cross section shown in FIG. 8 is a cross section corresponding to the cross section shown in FIG.

  In the above description, the form in which the periphery of the end 153A of the coil portion 153 is formed of the magnetic layer 155 has been described (see FIG. 2B).

  However, as shown in FIG. 8, insulating resin 154 </ b> A may be formed around one end 153 </ b> A of coil portion 153. The insulating resin 154A is made of the same resin material as the insulating resin 154 and is integrally formed with the insulating resin 154.

  When the gap between the one end 153A of the coil portion 153 and the coil portion 153 continuous around the one end 153A in a plan view is narrow, the plating process takes time if the magnetic layer 155 is formed around the one end 153A. And productivity may be reduced.

  In such a case, if the insulating resin 154A constructed of a photosensitive epoxy resin or the like is filled around the one end 153A, the magnetic layer 155 can be manufactured more easily than the case where the magnetic layer 155 is formed by plating.

  In addition, the gap between the one end 153A of the coil portion 153 and the coil portion 153 continuous around the one end 153A in a plan view is narrow, and a void may be generated in the magnetic layer 155 formed by plating. In such a case, an insulating resin 154A may be formed around the one end 153A instead of the magnetic layer 155. Since the insulating resin 154A is formed only by filling the periphery of the one end 153A, generation of voids can be suppressed and the inductance of the coil portion 153 can be made constant.

<Embodiment 2>
FIG. 9 is a cross-sectional view showing a wiring board 200 of the second embodiment.

  In the wiring substrate 200 of the second embodiment, an insulating film 252A similar to the insulating film 152 of the first embodiment is provided between the insulating layer 130 and the magnetic layer 151 of the wiring substrate 100 of the first embodiment. Is different from the wiring substrate 100 of the first embodiment.

  Since other configurations are the same as those of the wiring substrate 100 of the first embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.

  The wiring substrate 200 of the second embodiment includes an insulating film 252 instead of the insulating film 152 (see FIG. 2) of the wiring substrate 100 of the first embodiment.

  The insulating film 252 has a configuration in which an insulating film 252A is added to the insulating film 152 (see FIG. 2) of the wiring substrate 100 of the first embodiment. The insulating film 252A is formed between the insulating layer 130 and the magnetic layer 151. Portions of the insulating film 252 other than the insulating film 252A have the same shape and configuration as the insulating film 152 (see FIG. 2) of the wiring substrate 100 of the first embodiment.

  The insulating film 252A is made of, for example, an alloy of zinc and ferrite (Zn—Fe), as with the insulating film 152 (see FIG. 2) of the wiring substrate 100 of the first embodiment. Formed with.

  The insulating film 252A is integrated with a portion of the insulating film 252 other than the insulating film 252A (that is, a portion having the same shape and configuration as the insulating film 152 (see FIG. 2) of the wiring substrate 100 of Embodiment 1). Formed. The insulating film 252 is an example of a third insulating film.

  For example, when the magnetic layer 151 is formed directly on the insulating layer 130, a stable crystal direction may not be obtained in the magnetic layer 151. In addition, there may be a case where a planar distribution occurs in the thickness of the magnetic layer 151 and it is difficult to control the thickness. In such a case, the insulating film 252A may be formed.

  The insulating film 252A may be formed on the insulating layer 130 in a region where the magnetic layer 151 will be formed later.

  Here, for convenience of explanation, a part of the insulating film 252 added to the same part as the insulating film 152 of Embodiment 1 is distinguished as an insulating film 252A. However, the insulating film 252A is formed integrally with a portion of the insulating film 252 other than the insulating film 252A. For this reason, for example, it can be formed as described below.

  FIG. 10 is a diagram illustrating a manufacturing process of the wiring board 200 of the second embodiment.

  First, as shown in FIG. 10, an insulating film 252A1 is formed on one surface of the insulating layer. In Embodiment Mode 1, this corresponds to forming an insulating film over one surface of the insulating layer 130 in the step shown in FIG. 4A (step A). Of the insulating film 252A1, the portion located below the magnetic layer 151 shown in FIG. 9 becomes the insulating film 252A shown in FIG.

  Next, the magnetic layer 151 is formed on the insulating film formed on the insulating layer 130 in the process A by the same process as the process shown in FIGS. 4B and 4C (process B).

  Then, the magnetic layer 151 formed in Step B and the portion of the insulating layer formed in Step A that is not covered by the magnetic layer 151 (of the insulating film 130A in the insulating film 152A shown in FIG. 4D). An insulating film is formed on a portion similar to the portion formed above (step C).

  Next, the same processes as those in FIGS. 5A to 5D and FIGS. 6A to 6C are performed (process D). Further, an insulating film similar to the insulating film 152B illustrated in FIG. 7A is formed by a process similar to that in FIG. 7A (process E).

  Through the above steps A, C, and E, the insulating film 252 is completed. The insulating film 252 is obtained by integrating the insulating films formed in the process A, the process C, and the process E.

  Since the insulating film 252 is formed of, for example, a resin film such as polyimide, the surface can be made flatter than the insulating layer 130 included in the build-up substrate.

  Note that in the case where the characteristics of the coil 150 are improved by reducing the thickness of the insulating film 252 including the insulating film 252A, the thickness of the insulating film 252 may be reduced as much as possible.

  As described above, according to the second embodiment, by providing the insulating film 252A between the magnetic layer 151 and the insulating layer 130, the crystal direction of the magnetic layer 151 formed by the plating process can be made more stable. can do. In addition, the thickness of the insulator layer 151 can be easily controlled.

  Further, the wiring board 200 of the second embodiment can be modified in the same manner as the wiring board 100 of the modification of the first embodiment shown in FIG.

  FIG. 11 is a cross-sectional view showing a wiring board 200 according to a modification of the second embodiment. The cross section shown in FIG. 11 is a cross section corresponding to the cross section shown in FIG.

  A wiring board 200 shown in FIG. 11 is obtained by forming an insulating resin 154A around one end 153A of the coil portion 153, similarly to the wiring board 100 of the modification of the first embodiment shown in FIG.

  When the gap between the one end 153A of the coil portion 153 and the coil portion 153 continuous around the one end 153A in a plan view is narrow, the plating process takes time if the magnetic layer 155 is formed around the one end 153A. And productivity may be reduced.

  In such a case, if the periphery of the one end 153A is filled with an insulating resin 154A constructed of a photosensitive epoxy resin or the like, the wiring board 200 is manufactured more easily than when the magnetic layer 155 is formed by plating. be able to.

  In addition, the gap between the one end 153A of the coil portion 153 and the coil portion 153 continuous around the one end 153A in a plan view is narrow, and a void may be generated in the magnetic layer 155 formed by plating. In such a case, an insulating resin 154A may be formed around the one end 153A instead of the magnetic layer 155. Since the insulating resin 154A is formed only by filling the periphery of the one end 153A, generation of voids can be suppressed and the inductance of the coil portion 153 can be made constant.

  The wiring board and the method for manufacturing the wiring board according to the exemplary embodiments of the present invention have been described above, but the present invention is not limited to the specifically disclosed embodiments, and is claimed. Various modifications and changes can be made without departing from the scope.

100, 200 Wiring board 110 Core board 120, 120A, 120B, 120C Wiring layer 130 Insulating layer 140 Insulating layer 150 Coil 151 Magnetic body layer 152, 152A, 252, 252A Insulating film 153 Coil part 154 Insulating resin 155 Magnetic body layer 160A, 160B wiring 170, 170A, 170B, 170C wiring layer 180 insulating layer 190 insulating layer

Claims (11)

A first insulating layer;
A first magnetic layer formed of a plating film on the first insulating layer;
A planar coil formed on the first magnetic layer;
And a second magnetic layer formed of a plating film on the planar coil.   The wiring board according to claim 1, wherein an insulating film is formed between the planar coil and the first magnetic layer.   The wiring board according to claim 1, wherein the planar coil is formed of a plating film.   The wiring board according to claim 1, further comprising an insulating portion formed in a gap portion in plan view of the planar coil. A second insulating layer formed on the second magnetic layer;
A first wiring part formed on the second insulating layer; and
5. The one end of the planar coil is connected to the first wiring portion through a first via that penetrates the second insulating layer and the second magnetic layer. 6. Wiring board. A second wiring part formed on the second insulating layer;
The wiring board according to claim 5, wherein the other end of the planar coil is connected to the second wiring portion via a second via that penetrates the second insulating layer.   The wiring board according to claim 5 or 6, wherein the second magnetic layer has an opening through which the first via is inserted.   The wiring board according to claim 5, further comprising an insulating film formed between the second magnetic layer and the second insulating layer.   The wiring board according to claim 1, further comprising a third insulating film formed between the first insulating layer and the first magnetic layer. Forming a first magnetic layer on the first insulating layer by plating;
Forming a planar coil on the first magnetic layer;
Forming a second magnetic layer on the planar coil by a plating process.   The method for manufacturing a wiring board according to claim 10, wherein the planar coil is formed by plating.

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